Improvement in piston-valves for steam-engines



ALEXANDER BAUMANN, 0E LONDON, ENGLAND.

IMPROVEMENT IN `IMISTQN-VALVES FOR STEAM-ENGINES.`

Specification forming part of Letters Patent No. 139,357, dated May 27, 1873; application filed February 14, 1873.

To all whom it may concern:

r Be it known that I, ALEXANDER. BAU- MANN, temporarily residing in London, England, have invented a new and useful Improvement in Steam-Engine Valves, and I do hereby declare the following to be a full, clear, and exact description of the same, reference being. had to the accompanying drawing forming part of this specification.

The invention consists in cutting oit the steam from the main cylinder before its piston has reached its throw, by detached lead-Y ing-valves, one at each end of the main cylinder, and an intermediate one, all moved by the pressure of the steam that iills the main cylinder at or near the completion of each stroke. This piston-valves cut off' the exhaust of the main cylinder before the end of each'stroke, thereby forming therein a steamcushion, which checks the momentum of the main piston, and receives it with a yielding resistance like a spring, thus making high speed much safer. It is also economical, because the steam-cushion stores up power, which y is exerted in the re-action to send the piston back. A

Figure l is a horizontal section. Fig. 2 is a vertical section.

In the drawing, A represents a central valve having four disks, a al a2 a3, of nearly the same diameter, and arranged on the same spindle. B O are valves, each having three disks, b b1 b2 and c el c2, each set arranged on its own spindle, but one of each set of disks less in diameter than the other two. Each of these piston-valves is made of a single piece of cast-iron, while the central one is provided with rods A', which allow it to be moved by hand. All the cylinders D E F which surround these valves communicate with each other by passages d1 d2 d3 d4, as shown in Fig. l of drawing. The central cylinder D communicates with the steam entrance-port about `the middle of its length, and between the disks al a2, while the side-cylinders communicate with the exhaust-pipe by suitable ports b4 c4 are the ports which admit steam into the main cylinder G at each end. a/is the steam-supply, and b5 c5 the exhaust-passages of the main cylinder G. H is the piston-rod of the piston that reciprocates in the cylinder G. c6 is an annular groove to distribute the steam equallj,T around the piston-valve C, and allow it to pass up behind the disk c5, which is made for that purpose smaller than the' disks c2. The disks a a3 are also smaller than the disks a1 a2, to allow the passage therearound of the exhaust steam.

The operation is as follows: The pistons being placed as shown in' drawing, and the live steam, being entered between the disks. al a2, escapes through the channel d2 across the cylinder E and through the port c4 into v one end of main cylinder F, which forces the main piston forward to the other end of cylinder but as soon as the main piston has passed the exhaust-port c3 the exhaust steam rushes up therethrough around the recess c6, and behind the disk c5. This has the eiect of throwing down the piston G upon the steamcushion beneath the 'disk c, and allowing the exhaust steam to escape between the disks a al, and over the former. The air-spring then `returns piston C to its place, While the central piston A is forced.upward, and allowed 'to throw live steam through the passage d3 into the port b4 at the other end of main piston, which is thereby returned. It will thus be perceived that the piston passes the exhaustports 133 c3 before it reaches the end of its throw, and thus cuts oi the further egress of the exhaust steam, and forms a cushion for itself at each end of the cylinder. The escape of steam that has lled the main cylinder is thus prevented until the position of the main valve is completely reversed, which produces great certaintyand` uniformity in the operation. The auxiliary pistons, as well as the main one, are ystoppedr'at the ends of their strokes by steam cushions and by a layer of rubber, protected by"a thin sheet of rolled brass, that makes the operation noiseless.

Having thus described my invention, what I claim as new, and desire to secure by Letters Patent, is-

1. The main cylinder G, provided with exhaust-ports b3 ca arranged therein at a short distance from each end, as described, so that ranged in cylinders D E F, connected with the `piston will cut off the exhaust-steam beone another and with the main cylinder G, fore reaching the end of its throw, and thereby as and for the purpose set forth. form a cushion for itself at cach end of the cylinder.

2. The automatic valve mechanism, consisting of the valves A B C constructed and ar- ALEXANDER BAUMANN.

Witnesses ALFRED T. WATKINs. HAMILTON E. TOWLE. 

